Abstract
Diameter design of the riser is a very important link in offshore riser engineering, which will affect a series of parameter changes of the riser. In this paper, the riser is a variable-diameter riser with different cross-sections spliced by riser sections with diameters of 18, 25, and 30. In the wave-flow combined flume, dynamic response parameters such as strain-time history curve and root-mean-square of dimensionless strain were obtained by changing the outflow velocity and diameter of the riser, the effect of variable diameter on vortex-induced vibration of the riser was studied in detail. The results show that the vibration amplitude of the variable diameter riser varies with the axial position of the riser, but the frequency is dominated by the excitation of the thickest section riser; the variable diameter riser is always dominated by the first-order frequency in the outflow velocity range, and the relationship between the in-line and the cross-flow dominant frequency is always 2 times. With the increase of the flow velocity, the root mean square value of strain increases steadily.
Published Version
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